Piston-packing.



L. A. LAURSBN. PISTON PACKING.

APPLICATION FILED JAN. 21, 1914.

. 1,1 30,61 Patented Mar. 2, 19.15.

/ MIMI I lid 'Lil lhh lld l TA I 1 LAUEHS A. M'UESJEN, @IF MU CLAIRE, WISCONSIN.

lPISTON-IPAGMEYG.

Specification of Eetters Patent.

Patented Mar. 2, Mild,

Application filed January 21, 1am. Bartel 330. 313,551.

To all whom it may concern:

Be it known that l, Lemme A. Lioness, a citizen of the United States, residing at Eau Claire, in the county of Eau Claire and State of Wisconsin, have invented certain new and useful Improvements in Piston Packings, of which the following is a specii'icatio The present invention appertains to innprovements in piston packings, the primary object inview being to provide a peculiarly formed article of this nature whereby an effective seal may at all times, under any condition of wear and tear of either the cylinder or the packing itself, be maintained between thepiston and its cylinder walls. More specifically, this object may be defined by stating that it is comprehended by my invention to employ a packing which is coiled about the piston so that the wear on the outer periphery thereof is counteracted by the relative unwinding of the coil under action of pressure directed against the inner peripheral surface of said packing.

To more readily understand the advantages and function of my novel combination, it is explained that heretofore it has ben customary to provide pistons with metallic, resilient rings to prevent leakage of pressure past said piston, and it has loeen found necessary in order to render the same etlicient to employ generally a number of such rings and to specially form the ends of said rings with lapped joints, as well as to stagger the joint of one ring with respect to another. lln spite of such arrangement and precautions, however, in the course of time the wear between the piston rings and the cylinder walls becomes suficient to permit leakage and the expansive power of the rings is incapable of maintaining a liquid seal. To overcome this difficulty it has also been proposed to dispose springs beneath the picton rings tending to open the same as they wear, but this adds so materially the friction as to meet with disapproval. Hence it is that l. propose to surmount these ditliculties by using a flexible packing which is preferably of non-metallic material and substantially non-resilient in action, which packing, in the form ofa helical coil, is disposed in an annular peripheral groove in the piston, said groove being slightly wider than the packing in coiled shape, as a whole, and deeper than the packing in thickness. This loose mounting of said packing admits the pressure fluid beneath the packing so as to force the same against the cylinder walls. The piston is also formed with a clearance hetween it and the cylinder walls aforesaid whereby the pressure is exerted laterally and outwardly against the packing with equal force, providing an efiective seal of the character desired. Since a series of coils are provided, as the wear on the outer surface takes place the pressure expands the packingand this expansion is acconunodated by the coils unwinding without any chance of slippage past the packing occurring as is incidents to the opening of the joints under wear in the use of expansion packing rings such as hereinbefore mentioned.

With the above and other objects in view, this invention consists in the construction, combination and arrangement of parts all as hereinafter more fully described, claimed and illustrated in the accompanying drawings, wherein:

Figure l is a longitudinal sectional view taken through a cylinder and showing my particular form of packing disposednpon the piston; Fig. 2 is an end view with the cylinder head removed; and Fig. 3 is a perspective view of my special packing alone.

Throughout the following detail description, and on the several figures of the drawings, similar parts are referred to by like rererence characters. 7

Specifically describing the embodiment of my invention, the numeral 1 designates a cylinder of usual construction having the closure 2 for the same at one end and an apertured closure 3 for the otherend, through which last mentioned closure extends the piston rod at having at its inner terminal the piston head 5, said rod and head being hereinafter referred to as the piston. The outer periphery of the piston suitably formed wit a groove 6 which groove forms spaced flanges 7 and 7. Disposed within the groove 6 of the piston is the essentialfeature of my invention, namely, the packing member 8, most clearly shown in Fig. 3 of the drawing. This packing consists preferably of non-metallic and non-resilient material and is known generally to the cornniercial trade as hydraulic packing, it bein understood that such packing is compos of a textile fabric such as is customarily employed in articles of this nature and well known to those skilled in the art to which this invention refers. It will be noted by reference to the aforesaid Fig 3 that the packing member is in the form of a helical coil, there being shown in the drawing two of such coils but the said member may be formed of any desired number of such co v which, as will be obvious, may consist of more than the number of coils which is illustrated in the present drawing.

It will be noted by reference to Fig. 1 that the packing member 8 just described is loosely mounted in the groove 6 so as to provide a space both between the wallsof the flanges 7 and 7 and beneath the packing between the same and the bottom of the groove. This is an essential arrangement in my improvements as will be now particularly referred to. The iston is preferably formed smallerecircum erentially than the bore of the cylinder so as to leave a clearance space over the flanges? and 7' as indicated by the numeral 10.

- While the construction comprehended by my invention may be employed in various mechanisms, the operation and use of the same is described articularly with reference toa piston or hydraulic pumps in which it is particularly essential that the packing of said piston shall form an edective liquid seal to obtain the best results, which prevents leakage of the fluid over the piston member. As the fluid pressure, for instance water, is exerted against the iston when the same is moved in the direction of the arrow in Fig. 1, said fluid forces the packing toward the right and against the wall of the flange 'Z, leaving a assage for the fluid over the flange 7 and ownwardly about the packing and the inner wall of said flange to the bottom of the groove 6 beneath the packing. Therefore if the pressure against the piston amounts to ten pounds, such pressure will be exerted laterally against the packing and to an equivalent extent outwardly on the inner periphery of said packing 8. This prevents any leakage whatsoever past the piston, as will be obvious, particularly because the packing coil is expanded and pressed against the c linder walls to an amount equivalent to t e pressure which is exerted against the piston. By reason of the fact that the packing consists of a series of coils, as wear on the outer peripheral surface of the packing occurs the pressure beneath the packing tends to unwind the coil so as to counteract the extentof wear automatically as it takes place. .As the unwinding of the spiral takes place in the expansion of the pacmng the the cylinder walls is taken care of b coils more relatively to each other and since more than one coil is provided no space is formed between the terminals of the packing member, or in other words, a perfect circumferential contact entirely about the packing surface is maintained by this special form of packing member. As the pressure is exerted in the manner hereinbefore described against the packing it will be obvions that the coils of the packing are forced closely together into a very compact form. lit the pressure against the piston is increased from the amount hereinbefore mentioned to, say, one hundred pounds, the equivalent pressure is exerted outwardly on the packing member by reason of the fact that said fluid pressure is admitted beneath the same to act upon the inner peripheral of the spirally formed packing member in the packing groove isa very simple matter, as'the coils may be suitably contracted by manual ressure to admit of the insertion of'the piston into the cylinder. No special formation of joints is required in my piston member and it is not essential that the piston head itself shall be turned to the usual infinitesimal fraction of an inch smaller than the bore of the cylinder. As a matter of fact such a piston construction may be used ineither new or old cylinders and one of the veryadvantageous features of my peculiar packing is that any unevenness in the independent action of the "separate coils of the packing as the uneven portions are reached in the movement of the piston within the cylinder. Many other advantages might be mentioned and will be obvious to those skilled in the art to which this invention refers and I do not wish to be limited to the exact configuration of the packing member hereinbefore described and as illustrated in the drawings, as it will be apparexit-that changes might be made in the formation of the piston in order to enable the expansion of a packing coil in the manner described. Having thus described the invention, what is claimed as new is l 1 The combination with a liquid pressure cylinder, of a piston therein having an annular perlpheral groove and a packing in said groove comprising astrip of flexible elastic material wound in helical form about susceptible of radial deflection owing to its elasticity and flexibility for freely responding to surface variations of the c linder.

2. The combination with acylmder, of a piston having an annular peripheral groove and a packing in said groove comprising a strip of flexible material wound in helical form about the piston, the helix being of a a greater inner diameter than the diameter of the piston at the base of the groove and the helix being shorter than the width of the groove, the coils of the helix being movable relative to each other for enablin longitudinal circumferential travel of to strip and conse uent radial ex anslon and contraction o the helix for eely responding to surface variations of the cylinder. I

3. The combination with a liquid pressure cylinder, of a iston therein having an annular periphera l groove, and a packing in said oove comprising a strip of flexible plastic material wound in helical form about the piston, the helix bein of greater diameter than the diameter 0 the,

piston at the base of the groove and less in width than the width of the groove for enabling the pressure fluid to have access between the base of the groove and the inner surface of the helix for exerting radial outward pressure thereon, the coils of the helix being thus movable relative to each other for enabling variations in the circumference of the helix pro ortional to variations in the cylinder, eac portion of the packing strip contacting with the inner face of the cylinder being susceptible of conforming to the part' of the cylinder contacted with, in-

dependently of adjacent portions of the stri IE testimony whereof I aflix my signature in presence of two witnesses.

V LAURITS A. LAURSEN.

Witnesses: y

W. J. EBEBWEIN, E'rnm. Wmnm'r. 

